No abstract available

[en] Within research program on reactor safety, initiated by the Ministry of Research and Technology (BMFT) of the Federal Republic of Germany, the behavior of reinforced concrete slabs subjected to impact loads is studied. This research is essentially divided into two parts: the investigation of the behavior of deformable projectiles when striking nearly rigid targets as well as the measurement of the resulting impact force against time. The projectiles of tubular shape have the following dimensions: length about 6.00 m, diameter 0.60 m, maximum weight 10 KN, maximum velocity on impact is about 300 m/s. The results of these tests are needed to prove the basic assumptions underlying theoretical models. These theoretical models are used for the calculation of impact loads arising from a deformable projectile striking a rigid target. The examination of the bearing capacity of reinforced concrete slabs under short time loads. In these tests the loads are produced by the above described deformable projectiles. The slabs have the dimensions length/width 6.50/6.00 m, thickness 0.40...0.60 m. All measured quantities are compared with the results of numerical calculations. The expected research progress will not allow the first experimental results to be available before the beginning of the conference. Therefore, this paper is concerned with the theoretical work, required for the analysis of reinforced concrete slabs under impact loads. The influence of the parameters, used in assumed constitutive equations for reinforced concrete slabs is discussed together with several simplifications of the plate theory

[en] The effects of a postulated drop of the fuel element transport container into the storage pool were computed. The storage pool is a thick walled, water filled concrete cylinder, which is located directly beside the fuel element storage pool proper. Between both pools there is a gap through which the fuel elements can be transported below water. Together with the container the wall material behavior and height of fall were varied. The main task of the calculation was to find out the pressure wave which comes from the impact of the container on the water surface and which continues at the speed of sound in the water, is reflected on the bottom and comes back again. Because of two reasons a precise information is necessary; a drop should not be a faulted condition and therefore the density of concrete had to be guaranteed; at the bottom of the pool there is a bumper construction which is being kept dry from the water by a metal plate. This bumper should only catch up the falling container without being filled with water unless the container hits the plate. Therefore the support of the metal plate had to absorb the pressure energy. On the whole 5 cases are considered within this study: 1) normal container, stiff wall, height of fall 2.30 m; 2) like cases 1, but with the concrete wall in the mathematical model; 3) like case 2, but reduced height of fall of 0.90 m; 4) like case 3, but 50 times stiffer transport container; 5) like case 3, but twice as much reinforc

[en] This paper presents a simple dynamic cavity expansion approach to the penetration of slender, axisymmetric, rigid projectiles into compressible, strainhardening targets under axisymmetric conditions. Furthermore, it is not reasonable to expect a single theory to cover all targets and all velocities of impact. A non-dimensional number has been defined to provide parameter for discussion of scaling and range of validity of the theory. Basic assumptions of Goodier, Hanagud and Ross theories have been retained. After imbedding, the compressive normal stress at the nose tip is assumed to be given by the spherical cavity expansion theory that corresponds to the smaller of the cylindrical radii at the target surface or the base, instantaneous velocity and acceleration of the projectile. The resulting expression for the normal stress consists of a part p that depends on the target intertia and a part p which does not. Following Goodier, p is assumed not to vary along the nose (frontal surface) of the projectile. The variation of p along the frontal surface is obtained in two different ways. The first approach is to generalize Goodier's cosine variation to accommodate conical and ogival nose shapes. The second approach follows an approximate representation of target particle velocity v and acceleration a. Basic frame work for this representation is as follows. (a) A particle at the nose tip moves with the instantaneous projectile velocity. (b) Component of v normal to the projectile nose is equal the corresponding component of projectile velocity. (c) v is continuous along the nose. (d) Relative a fixed observer, tangential component of v is zero at the base. (e) The variation of tangential component of v between nose tip and nose base follows from similar problems in fluid mechanics

No abstract available

No abstract available

No abstract available

[en] Calculations concerning the impact of airplanes upon nuclear power plant buildings usually imply that the building 'acts' as a rigid target. This assumption is justified for considerations concerning the structural integrity of the building being hit. However, for investigating induced vibrations of components within the structure, this approach might -in general- be too conservative. It is expected, that yielding of the structure during impact reduces the peak values of the loads and changes the temporal behavior of the load function which is obtained for a rigid target. To calculate the changes of the load function which are due to deformations of the structure, Riera's method is extended for the case of a yielding target. In view of the applications of the calculations to the impact of airplanes upon buildings which are constructed to withstand loads of this kind without serious damage and without large deformations, it is possible to simplify the calculations to some extent. That is, the investigations need not take into account in detail the behavior of the target during impact. The calculations are performed with a one-dimensional model for the projectile. The direction of impact is perpendicular to the target surface; direction of impact and projectile axis coincide. The calculations were performed for several initial velocities of the projectiles simulating a fast flying military airplane. Variations of the peak values of the load functions as compared to corresponding values for a rigid target do not exceed about 10%. The overall temporal behavior of the load curves turns out to be not very sensitive to the yielding of the target, though, in some cases displacements in time of the peak positions within a single load curve do arise

[en] Due to the high population density, in Belgium PWR power plants are designed against aircraft impacts. A double wall is used for the containment shield. The lack of relevant data and specifications for such a loading on the non-prestressed external wall led us to determine the suitable safety criteria, the most appropriate materials to be used and the corresponding limit state design through dynamic and plastic analysis. Our technical choices and calculation results are summarized below. The safety criteria consisted mainly in adopting an ultimate limite state design for the allowable compression stress on concrete and the yield stress for the allowable tension stress on reinforcement. The plastic calculations have been carried out by successive approximations of the final state instead of a step by step analysis. An elastic dynamic analysis for an impact at the top of the dome has been made with the MARC program. It justified a D.L.F. of 1.15 for the shear forces. The ULS design without crack limitation made the use of high strength steel for the main reinforcement fully efficient. This allowed an important saving on the reinforcement cost. Static and dynamic tests have been carried out on high grade bars. Among other interesting results these tests showed a strain velocity of 100% per sec. and an increase in the ultimate strength under rapid loading

[en] Nuclear powerplant facilities and many other structures need protection against missiles generated by tornadoes and explosions. The missile impacts result in both local and overall effects on barriers or targets. The local effects are characterized by penetration, perforation, and backface spalling or scabbing of the target material. The overall effects of missile impact on structural stability are commonly evaluated in terms of the flexural and shear behavior of the target. Empirical formulas are presented to determine the local effects on concrete and steel barriers. Procedures are given for determining the design loads for overall effects. Design methods are described